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Патент USA US3026444

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March 20, 1962
P. M. MCPHERSON
3,026,435
ULTRAVIOLET LAMP
Filed Sept. 16, 1960
5 Sheets-Sheet 1
B
AT TORNEYS 4
March 20, 1962
3,026,435
P. M. MCPHERSON
ULTRAVIOLET LAMP
Filed sept. 16, 1960
5 Sheets-Sheet 2
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ATTORNEYS
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March 20, 1962
P. M. McPHl-:RSON
ULTRAVIOLET LAMP
Filed Sept. 16, 1960
3,026,435
„
5 Sheets-Sheet 3
GAS INLET
56
¿ATTORNEYS
March zo, 1962
`
P. MMCPHERSON
3,026,435
ULTRAVIOLET LAMP
Filed sept. 16, 1960
5 sheets-sheet 4
ATTORNEYS
March 20, 1962
P. M. MCPHERSON
3,026,435
ULTRAVIOLET LAMP
Filed Sept. 1G, 1960 '
5 Sheets-Sheet 5
INVENTOR.
BY
ATTORNEYS
,
‘United States arent
f vfice
SßZbALÈS
Patented Mar. 20, 1962
1
2
3,026,435
ot the present invention, reference should be had to the
following detailed description taken in connection with
UL'I'RAVIOLET LAX/IP
Pani M. McPherson, Acton, Mass., assigner to McPher
the accompanying drawings wherein:
spn Instrument Corporation, Acton, Mass., a corpora
FIG. 1 is a top plan view, partly broken away, of a
vacuum ultraviolet lamp embodying the present inven
Filed Sept. 16, 1960, Ser. No. 55,466
12 Claims. (Cl. 313-22)
tion, shown in conjunction with a fragment of a spec
tion of Massachusetts
trometer;
FIG. 2 is a vertical cross-sectional view, partly bro
The present invention relates to the generation of ultra
ken away, of the lamp of FIG. l, the section being taken
violet radiation and, more particularly, to a high power 10 substantially along the line 2--2 of FIG. 1;
ultraviolet lamp for use in conjunction with spectro
FIG. 3 is a cross-sectional view, partly broken away,
scopic apparatus.
of the lamp of FIG. 1, the section being taken substan
That part of the electromagnetic spectrum having
wavelengths shorter than 2,000 A. is frequently called
the vacuum ultraviolet region because the high absorp
tion of such wavelengths by most gases often requires
the evacuation of spectroscopic apparatus utilizing such
the section being taken substantially along the line 4-4
wavelengths. Thus, a typical spectrograph for use in
this region comprises an entrance slit through which
ultraviolet radiation is transmitted from a source, a dif
section view of a part of the lamp of FIG. l; and
FIG. 6 is a perspective, disassembled View of the lamp
of FiG. 1.
fraction grating for dispersing this radiation from the
Generally the illustrated embodiment of the present
invention, with reference to FIGS. l, 2 and 6, comprises
entrance slit into a spectrum, an exit slit for transmitting
a selected part of this spectrum from the dittraction grat
ing to desired auxiliary apparatus and means for evacu
vating the diffraction grating chamber.
tially along the line 3-«3 of FIG. l;
FIG. 4 is a cross-sectional view of the lamp of FIG. l,
of FIG. 1;
FIG. 5 is an enlarged, fragmentary, partially crossed
a source 20 of ultraviolet light in conjunction with a
spectrograph 22 that includes: an entrance slit 24
The lamp for 25 through which ultraviolet radiation from lamp 20 enters;
a diffraction grating (not shown) of conventional design
such a spectrograph generates ultraviolet radiation by
applying a high potential across an ionizable gas in a
tube that is sufticiently narrow to concentrate the result
ing radiation in a narrow beam. In order to maximize
that disperses the radiation from the entrance slit into a
spectrum; an exit slit (not shown) of conventional de
sign through whic'n a selected portion of the spectrum
the energy transmitted through the slit from the lamp, 30 is transmitted from the grating; and a Vacuum pump
this tube is oriented perpendicularly to the plane of the
(not shown) of conventional design for maintaining the
slit so that emission of the beam in an axial direction
interior of the spectrograph at reduced pressure. The
from an end of the tube is eiïected. In the 1000 to 2000
slit is shown in FiG. l at 24 as being provided by a plate
A. region, it may be practicable to confine the gas with
25 that is mounted upon a support 28. Support 2S pro
in an envelope which eiiîciently transmits ultraviolet 35 vides an aperture 30, through which radiation from slit
radiation. However, in the region below 1000 A., high
25 may enter the evacuated interior 32 of the spectro
absorption by most solid materials renders the design of
graph.
a suitable envelope impracticable. Accordingly, it is nee
Generally lamp 20 includes an ultraviolet source in the
essary in this short wavelength region to transmit energy
form of a capillary tube 34 that extends between an
_directly from the plasma of the lamp through the slit 40 anode 36 and a cathode 33. Typically, capillary tube
of the spectrograph. Furthermore, because of a require
34 ranges from lÁs to 1/2 inch in diameter. Anode 35
men for the generation of ultraviolet radiation of de
is provided with a central bore 40, into which snugly
sired intensity, high potential difference is necessary
projects one end of capillary tube 34. Cathode 38 is
across the plasma and great heat is produced in the
provided with a central bore 42, into which snugly pro
plasma. The present invention contemplates a simpli
jects the other end of capillary tube 34. The seals be
fled construction of the foregoing type characterized by
tween the outer periphery of capillary tube 34 and the
eñîcient heat exchange for preventing excessive heating
inner periphery of bore 40 and between the outer pe
of the lamp, eñective mounting and shielding of com
riphery of capillary tube 34 and the inner periphery of
ponents to facilitaterhandling and eliminate hazard and
bore 42 is ensured by rubber-like O-rings 44 and 46.
limited mechanical communication between the evacu
Cathode 3S is mounted upon anode 36 by three in
50
ated spectrograph chamber and the pressurized plasma
sulating posts 4S, 50 and 52, which electrically isolate
tube in order to minimize leakage of plasma from the
cathode 3S from anode 36. An ionizable gas, preferably
lamp to the spectrograph.
a noble gas such as argon or an inert gas such as nitrogen,
Objects of the present invention are: to provide a
is introduced into the axial capillary oriñce 54 of capil
combination of the foregoing type wherein the conduit
lary tube 34 through a fitting 55 and a bore 58 in cathode
defining the optical path for radiation from the plasma
36 that communicates with bore 40 of cathode 36. Bores
49 and 42 of anode 36 and cathode 33 are designed to
trograph in such a Way as to confine mechanical com
contain a substantial quantity of this gas. The arrange
munication between the spectrograph and the lamp to
ment is such that the pressure of the gas within capillary
the cross-sectional area of the slit; to provide a lamp
orifice 54 is maintained constant by the pressure sinks
60
for an apparatus of the foregoing type in which all com
constituted by bores 40 and 42. A suitable pressure con
is sealed directly to the face defining the slit of the spec
ponents are mounted on a grounded electrode and with
trol (not shown) is associated with ñtting 56 in order to
in a grounded shroud for facility and safety; and to pro
maintain the pressure of the gas within the system con
vide a lamp of the foregoing type in which the plasma
stant notwithstanding its escape from the system in minute
tube, which is composed of an electrical insulator, is 65 quantities through slit 24 in a manner to be described
below.
mounted between the anode and the cathode, which are
Capillary tube 34 is shaped to include a water jacket
composed of electrical conductors, in such a Way that
the grounded electrode and tube may be Water cooled
60 (FlG. 4), through which water is circulated between
an inlet 62 and an outlet 64. Water jacket 60 serves
and the “hot” electrode may be air cooled.
to maintain capillary tube 34 at a predetermined tem
Other objects of the present invention will be obvious
70
perature notwithstanding the heat generated by the plasma y
`-»and will in part appear hereinafter.
For a fuller understanding of the nature and objects
within capillary oriiice 54. This plasma Ialso transfers
3,026,435
3
4
departing from the scope of the present invention, it is
intended that all matter >contained in the above descrip
tion or shown in the accompanying drawings shall be
heat to anode 36 and cathode 38. Anode 36 is provided
with an annular bore 66 into which water is fed through
a fitting 63 and from which Water is fed through a Íit- ,
interpreted in an illustrative `¿and not in a limiting sense.
ting 7d. Fitting 7G Vcommunicates with inlet 62 of capil
lary water jacket 60 Vthrough a tubeV 71 so VthatV both
What is claimed is:
l. in combination with spectroscopic means including
an evacuated chamber, an entrance-¿slit communicating
therewith through which ultraviolet radiation may be
transmitted, a dispersion means for dispersing (the ra
anode 36 and water jacket 60 circulate the same stream
of water. Cathode 38, which because of its extremely
lowV potential must Vbe _electrically isolated, is provided
with a multiplicity of ñns 72 that are air cooled by a
suitable motor driven fan 74. Motor driven fan 74
is mounted on a cage 76 of generally cylindrical contigura
tion. One end of cage 76 is aiiixed to anode 36 as at
7S andthe other end of cage 76 is closed by a cap 80.v
diation from the entrance slit into a spectrum and an exit
slit communicating for selectively transmitting: a re
stricted portion of said spectrum, an ultraviolet lamp com
prising first electrode means providing a seat, Vsecond
electrode means providing a seat, spacing means between
said second electrode means and said iirst electrode means
Cage 76 is articulated in order to permit free ilow of air
through iins 72. Anode 36, cage 76 and cap 80 com
pletely surround cathode 38 in such a way as to prevent
for mechanically connecting and electrically isolating said
second electrode means and said'iirst electrode means, a
manual contact of cathode 38 when the lamp is in opera
tube providing a central oriiice, one extremity of said
tion. Anode 36, cage 76 and cap 80 are grounded so
tube being received hermetically by said seat of said first
that they may be freely handled without danger.
As is Vbest shown in FIG. 5, anode 36 abuts against 20 electrode means, the vother extremity of said tube'being
received hermetically by the seat of said second electrode
a plate ,82, to which it is sealed by concentric O-rings 84
and V86. Plate S72 is provided with an outwardly project
means and means for introducing a gas into said cen
ing hub 8S. A central bore 9i) extends through hub 88
and plate 82.Y Atrthe center of plate 82 is aiiixed an
aperture disk 92. Projecting toward plate 26, which pro
vides slit 24, from within bore 90 is a hollow tubelet 94.
The outer periphery of tubelet 94. contacts the face of
plate 26 and is sealed thereto by means of a suitable O
tral
oriiice.
A'
` e
'
2. ln the combination of claim l, a water jacket sur
rounding said tube.
' 3. In the combination of claim 2, said second elect-rode
means providing a duct, and a> coolant forcirculation
through _said duct and said water jacket.
i
` 4. ln the combination of claim 3, a cage enveloping
ringV 97. The rearward end portion of tubelet 94 is pro
vided with a peripheral slot 95. Projecting into slot 95 30 said iirst electrode means and connected to said second
electrode means, said 'second electrode means and said
is a ñnger 96 that extends from and is eccentric to a shaft
cage _being grounded, said first electrode means being at
98. Shaft 98 is rotatable in a bore 100. By rotating
a potential other than ground.
Y
the knurled head 102, which is attached to the outer end
>5. In the combination of claim l, a reciprocable hollow
of shaft 98, tinger 96 is caused to bear against slot
95 in such a way as to cam the outer end of tubelet 94 35 sleeve communicating with said bore of said second elec
Ytrode means and means for wedging said reciprocable
against plate 26.
sleeve against said entrance slit of said spectroscopic
In operation, fan 74 is energized by such means as a
means.
Y
switch 134. The pressure of the ionizable gas within
6_. In combination with spectroscopic means including
bore 40 of anode 36, capillary oriiice 54 and bore 42 of
cathode 38 isY built up. Spectrograph cavity 32 is evacu 40 an evacuated chamber, an entrance slit communicating
therewithn through which ultraviolet radiation may be
ated. Water is ilow through inlet 68 of anode _36, from
transmitted, a dispersion means for dispersing the radia
outlet 79 to inlet 62, through Water jacket 60 and from
tion from theV entrance slit into a spectrum and an exit
outlet 64. A-negative potential of from 10,000 to 30,000
slit communicating for selectively transmitting a re
volts, and preferably of about 15,00 volts, is applied to
cathode 38.` In consequence, a dischargeioccurs through 45 stricted portion ofv said spectrum, an ultraviolet lamp
comprising lirst electrode means providing a seat, second
the gas within capillary orifice 54 in such a Way that
electrode means providing a seat, spacing Vmeans between
heavy cations are directed toward cathode 38 thereby
said iirst electrode and said second electrode means for
rendering the pressure toward cathode end of capillary
mechanically connecting and electrically isolating said
oritice 54 higher than the pressure at the anode end there
of. The slivht leakage of gas through slit _24 into the 50 second electrode means and said ñrst electrode means, a
tube providing'a central orifice and a lsurrounding water
evacuated chamber 32 of the spectrograph is minimized
jacket, said water jacket being composed of an insulat
by tubelet 94 which abuts against the face of plate 26.
ing material, one extremity of said water jacket being re
Typically, the pressure in the spectrograph is maintained
ceived
hermetically by said seat of said iirst electrode
at an order of a few microns of mercury and the pres
sure in the lamp is maintained at an order of a few 55 means, the> other end of said water jacket being received
hermetically by said seat of said >second electrode means,
means for introducing a gas into said central orilice, said
second electrode means providing a duct means for circu
millimeters of mercury.
The present invention thus provides a simply .designed
ultraviolet lamp that is capable of directing intense ultra
violet radiation directly from a plasma through the slit
latingU coolantthrough said ductl and throughV said water
window. The intense radiation is made possible by a
high potential ditierence across the plasma and an eili
Ycient cooling system. All of the components are mounted
7. in the combination of V'claim 6, said first electrode
means being at a potential other than ground, and a cage
of an evacuated spectrograph without an intermediary 60 jacket, tins on said second electrode means, and'means
Vfor blowing air over said tins. "
'
’
enveloping said first electrode means and connected to
simply in such `a way as to eliminate danger by virtue
said second electrode means, said second electrode means
of a grounded cage that completely envelops a low po 65
and said cage being grounded.
tential cathode and that is mounted on a grounded anode.
In alternative embodiments of the present invention,
the polarity of the electrodes are reversed such that elec
trode 36 is the cathode at ground and electrode 38 is the
S. ' An ultraviolet lamp comprising -tir’st electrode means
providing a seat, second electrode means providing- a
seat, spacing means between said second electrode means
anode at elevated potential or `an alternating current is 70
applied across the electrodes. -In another alternative
embodiment of the present invention, the ionizable gas is
fed into the system through bore 42 rather than bore 40.
Since certain other changes may be made in the above
and said iirst electrode means’for mechanically connect
ing and electrically isolating said second electrode means
` and said iirst electrodeV means, and a tube providing a
central oriiice, one extremity of said tube being received
hermetically by said seat of said iirst electrode means,
_described embodiment of the present invention without 75 the other extremity of said tube being received hermetical
3,026,435
5
6
ly 'oy said seat of said second electrode means, means for
introducing a gas into said central oriñce, said first elec
trode means being at a potential other than ground, and
therebetween, one of said electrode means providing an
opening therethrough communicating with said tube
means, means for introducing a gas into said tube means,
a cage enveloping said ñrst electrode means and con
means for applying a potential between said ?rst electrode
nected to said second electrode means, said second elec
trode means and said cage being at ground potential.
9. The ultraviolet lamp of claim 8, wherein a water
means and said second electrode means, means for mount
jacket surrounds said tube.
lO. The ultraviolet lamp of claim 9, wherein one of
sleeve means remote from said opening, and means for
ing a sleeve, means for> reciprocal motion in communica
tion with said opening, gasket means at the end of said
reciprocating said sleeve means.
said electrode means provides aV duct, and a coolant is 10
12. The ultraviolet lamp of cla-im l1 wherein said
provided for circulation through said duct and said water
gasket means is an O-ring.
jacket.
l1. An ultraviolet lamp comprising first electrode
means, second electrode means and tube means extending
No references cited.
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